import java.math.BigInteger;
import java.util.Scanner;

public class JieCheng {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        BigInteger num = new BigInteger("1");
        for(int i = 2;i<=n;i++){
            num = num.multiply(new BigInteger(i+""));
        }
        System.out.println(num.toString());
    }
}
